Gas turbines are widely used in industrial and power generation operations. A typical gas turbine includes an axial compressor at the front, one or more combustors around the middle, and a turbine at the rear. Ambient air enters the compressor, and rotating blades and stationary vanes in the compressor progressively impart kinetic energy to the working fluid (air) to produce a compressed working fluid at a highly energized state. The compressed working fluid exits the compressor and flows to the combustors where it mixes with fuel and ignites to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases expand in the turbine to produce work. For example, expansion of the combustion gases in the turbine may rotate a shaft connected to a generator to produce electricity.
It is widely known that a leaner fuel-air mixture reduces the nitrous oxides produced from combustion. However, a leaner fuel-air mixture introduces flame instability in the combustor, increasing the chance of a lean blow out (LBO) event that might interrupt service provided by the gas turbine. The addition of hydrogen to the fuel can reduce the occurrence of lean blow out, improve emissions, and enhance the overall operation of most combustors, such as Dry Low NOx (DLN) combustors. Inasmuch as hydrogen is difficult to transport safely, an on-site production capability for the amount of hydrogen needed to supplement the fuel would be desirable. Various methods are known in the art for producing hydrogen on-site. For example, autothermal reformers (ATR) and steam methane reformers (SMR) may be used to produce a hydrogen enriched fuel. In general, these reformers expose a catalyst, such as nickel, to a fuel, such as natural gas, in a high temperature and pressure environment to produce pure hydrogen, and the exothermic catalytic reaction produces a very high temperature exhaust that can present a problem for valves, seals, and other system components. In addition, SMR reformers typically require an external source of steam which may not be readily available. Lastly, the pressure of the hydrogen enriched exhaust stream is generally lower than the pressure in the gas turbine combustor. As a result, a separate compressor is needed to increase the pressure of the hydrogen enriched exhaust stream so it can be injected into the combustor of the gas turbine. Therefore, an integrated gas turbine system that can produce hydrogen enriched fuel on-site would be useful.